What is Maxwell's Demon?

Maxwell's Demon is a thought experiment proposed by physicist James Clerk Maxwell to challenge the second law of thermodynamics. The demon operates as follows:

1. Setup: Imagine a container divided into two compartments filled with gas molecules with a small door between them.
2. Demon's Role: A hypothetical "demon" is situated at the door and can open and close it to allow only fast-moving molecules to pass from one side to the other.
3. Outcome: Over time, one side of the container becomes hotter (with faster molecules), and the other side becomes cooler. This creates a temperature difference that could, in theory, be used to perform work, seemingly violating the second law of thermodynamics which states entropy (disorder) in an isolated system should increase over time.

The paradox lies in how the demon can reduce entropy without expending energy. Attempts to resolve this include considering the energy the demon uses to measure and move molecules and the brain's memory erasure process. Physicist Ralph Landauer provided key insights, suggesting that the demon's memory erasure creates enough entropy to uphold the second law, thus preserving thermodynamics' integrity 1.

The discussion of Maxwell's Demon connects deeply to the concepts of molecular intelligence and thermodynamic efficiency in systems like computation and life itself 2.